The Molecular Cytology Core Facility (MCCF) underpins all the basic and clinical research at MSKCC involving the interrogation of proteins or nucleic acids in cells, tissues and tumors. The MCCF retains state-of- the-art equipment and an array of imaging tools and a team of highly talented technical assistants and as such provides both a service and one-on-one training enabling faculty and their trainees to work independently with high-end instrumentation. A resource of validated antibodies for automated or manual histology is a feature of the Core's rapid and reliable service used by investigators working with animal tumor models or patient samples. To explore the cell biology of cancer cells at high spatial and temporal resolution, the Core's in-house expertise enables the power of a superb suite of confocal microscopes to be accessible not only to cell biologists but also to the wider community of members of the Cancer Center. Imaging modalities for molecular detection available to the researchers at the MCCF are optical microscopes, including wide field (epifluorescence, bright field, polarizing and DIC), confocal (raster scanning, line scanning and spinning disc), time lapse microscopy, FLIM and digital scanners. Experiments involving uncaging experiments, FRAP and FRET, and Ratio imaging of calcium ions are also carried out at the MCCF. In addition to assistance and training on image acquisition, the MCCF staff provide assistance to researchers in image processing and analysis using Velocity, MetaMorph, Imaris and MatLab software. The broad range of services and collaborative work provided by the Molecular Cytology Core has supported the research of 120 investigators in the past year. During the past grant period the work of the Core has contributed to 315 publications of researchers from 5 research programs. For example, with the assistance of the Core, Studer and Tabar demonstrated that neural rosette cells represent the first characterized neural stem cell stage capable of responding to patterning cues that direct differentiation toward region-specific neuronal fates. The Core provided immunohistochemistry and image analysis critical to this work.